[Serusers] ser and client behind nat,no audio...urgent

Ashling O'Driscoll ashling.odriscoll at cit.ie
Thu Feb 3 12:29:14 CET 2005


I really need to sort out my nat situation with ser as soon as
possible....Im beginning to believe its not doable.

SER is behind nat and clients are behind nat (one on the same lan as
ser) and the other on a totally different nat. Both clients register
with a public address and port forwarding the nat router forwards the
sip traffic to ser. I know this situation is horrible but I cant do
anything about it. I have setup nathelper and rtpproxy on ser. 

Now if a client behind nat (which is on the same lan as ser) rings
another client behind nat (on same lan as ser), then everything works
fine and the audio flows. However if a lcient behind (on the same lan
as ser) rings a client on behind on nat on DIFFERENT network to ser,
then no audio flows. I realise this is because of that fact that they
both have internal IP addresses and a middle man is needed. That is
why I set up rtpproxy. But will rtpproxy work when its also behind
nat??....

I've did an ethereal sniff of remote client and also of ser when
calling from my client on ser lan to the remote client and the
results are below.

My config was a jumble of various emails from the mailing list so Im
going to start from scratch and say my ser.cfg is just like the basic
one included in the below link.

http://www.informatik.uni-bremen.de/~prelle/terena/cookbook/Cookbook_D
2/ch04s07.html#d0e5091

Please, Please give me guidance. I know this is a horrible nat
situation but i just cant figure out how to solve it or if it can be
solved.

Thanks,
Aisling

ethereal sniff of remote client (not on same lan as ser, but behind
nat)xxx.xxx.xxx.xxx is my public address

SIP INVITE xxx.xxx.xxx.xxx. -> 10.0.1.21 (internal address of remote
client)
100 trying 10.0.1.21 -> xxx.xxx.xxx.xxx
180 ringing 10.0.1.21 -> xxx.xxx.xxx.xxx
200 ok 10.0.1.21 -> xxx.xxx.xxx.xxx
rtp 10.0..1.21 -> xxx.xxx.xxx.xxx

ethereal sniff of ser (with nathelper and rtpproxy) but behind nat

INVITE 172.16.3.28 (internal address of client on same lan as ser) ->
xxx.xxx.xxx.xxx
invite xxx.xxx.xxx.xxx.172.16.3.15(internal address of ser)
100 trying 172.16.3.15 -> xxx.xxx.xxx.xxx
invite 172.16.3.15 -> 157.190.70.231(public address of remote client)
100 xxx.xxx.xxx.xxx -> 172.16.3.28
100 trying 157.190.70.231 -> 172.16.3.15
icmp 172.16.3.15 -> 157.190.70.231 dest unreachable
same happens for 180 ringing and 200 ok.


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